1. Field of the Invention
Aspects of the present invention relate to a USB circuit device, and more particularly, to a USB circuit device that prevents reverse current and that is in compliance with USB specifications.
2. Description of the Related Art
A universal serial bus (USB) interface is a general-purpose tool that connects a personal computer (PC) with an external device. The USB interface has an additional power signal that provides power to the external device if the device does not have its own power source. However, when an external device that has its own power source is connected to the PC, if the power of the external device is not shut off when the power of the PC is shut off, a reverse current may be induced from the external device to the PC. The reverse current influences the operation of the PC and causes problems.